In a circle with center O AC and BD are diameters. The center angle of the AOD is 142 degrees. Find the inscribed corner ACB.

∠АОВ and ∠АОD are adjacent, which means ∠АОВ + ∠АОD = 180 °.

Therefore, ∠АВ = 180 ° – ∠АОD = 180 ° – 142 ° = 38 °.

∠АСВ rests on the arc AB and the central ∠АОВ rests on the arc AB.

Because ∠АСВ – inscribed, and the inscribed angle is equal to half of the central angle resting on the same arc, then we find its value:

∠АСВ = ½ * ∠АВ = ½ * 38 ° = 19 °.

Answer: ∠АСВ = 19 °.



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